1. Field of the Invention
The invention relates to trocars. More particularly, the invention relates to a multi-angled duckbill sealing assembly for trocars.
2. Description of the Prior Art
A trocar assembly is a surgical instrument that is used to gain access to a body cavity. A trocar assembly generally comprises two major components, a trocar sleeve, composed of a trocar housing and a trocar cannula, and a trocar obturator. The trocar cannula, having the trocar obturator inserted therethrough, is directed through the skin to access a body cavity. Once the body cavity is accessed, laparoscopic or arthroscopic surgery and endoscopic procedures may be performed. In order to penetrate the skin, the distal end of the trocar cannula is placed against the skin that has been previously cut with a scalpel. The trocar obturator is then used to penetrate the skin and access the body cavity. By applying pressure against the proximal end of the trocar obturator, the sharp point of the trocar obturator is forced through the skin until it enters the body cavity. The trocar cannula is inserted through the perforation made by the trocar obturator and the trocar obturator is withdrawn, leaving the trocar cannula as an access way to the body cavity.
The proximal end portion of the trocar cannula is typically joined to a trocar housing that defines a chamber having an open distal end portion in communication with the interior lumen defined by the trocar cannula. A trocar obturator, or other elongated cylindrical surgical instruments axially extend into and are withdrawn from the trocar cannula through the proximal end portion of the chamber defined by the trocar housing.
It is the present practice to provide the chamber of the trocar housing with a sealing mechanism, such as a sealing grommet or gasket, through which the instruments extend. The sealing mechanism seals against the outer surface of the inserted instruments and thereby prevents fluids and insufflation gas from leaving or entering the body cavity through the trocar cannula. In fact, insufflation gas does not enter the trocar cannula at any time due to the higher abdominal pressures encountered during medical procedures.
Some current trocar assemblies utilize a “duckbill” seal assembly. Duckbill seal assemblies include a pair of opposed valve members which open and close in much the same manner a duck opens and closes its bill. Duckbill seal assemblies generally include a straight wall angle which defines the flex point for the opening and closing of the duckbill seal assembly. However, by limiting the wall angle to a single value, manufacturers must consistently trade off between the overall seal height, drag force, inversion and other trocar assembly parameters.
Prior art trocars generally call for an initial design optimization selecting a 30-45 degree wall angle to minimize the overall height and drag force. The choice of a 30-45 degree wall angle is, however, made at the expense of tear reliability because the limited angle results in more direct contact between the instruments and the surface of the seal assembly. Studies have indicated the wall section next to the center ribs of current duckbill seal assembly is susceptible to local buckling and thus tear failures occur at angles where the instrument contacts the seal assembly at angles approaching 90 degrees. That is, where the trocar obturator or other insertion tool contacts the duckbill seal assembly at angles approaching 90 degrees, local buckling and tear failure of the duckbill seal assembly becomes more likely.
Accordingly, there is a need for a trocar assembly that includes a duckbill seal assembly improving tear resistance and buckling prevention. The present invention provides such a duckbill sealing assembly.